Power brake



OC. 17, 1944. G E. PORTER 2,360,578

POWER BRAKE Filed Aug. 26, 1942 V58 nl lsllwu BB a ' Gttorneg Patented Oct. 17,

My invention relates to hydraulic devices which are operated by the controlled application of fluid under pressure, and relates in particular to a uid applying device especially useful for the operation of hydraulic brakes of aircraft and-automotive vehicles.

It is an object of the invention to provide a device for applying iluid under pressure to an expansible unit such as a hydraulic brake cylinder, wherein the force applied to the expansible unit is a predetermined multiple of the force It ls an object of the invention to provide brake operating means having maximum sensitivity in response to control. This sensitivity makes possible the substantially instantaneous application of the brakes from a release or applied condition, thereby avoiding delay encountered in many brake devices between the time the conf trol is rst applied to the operating lever and the time the brakes are actuated, and also the fault found in many hydraulic brakes, 'especially those used in aircraft, over-application of the brakes is avoided. Over-application of the brakes when the controls are first operated often results in loss of control of the aircraft, or at least causes a Jerky retarding of the speed of the aircraft on the ground.

A further object of the invention is to provide l a brake operating means which gives continuous and sensitive control of the brakes, so that there is no liability of the braking effect running away from the actuator or foot pedal. In the invention the movement of its pressure applying pis- 40 ton is maintained always in unison with the movement of the operating lever or foot pedal, thereby avoiding the dimculties found in many brakes, consisting in an initial application of fluid pressure to the'hydraulic brakes materially in excess of the intentions of the operator.

A further object of the invention is to provide a brake operating device having a iiuid pressure receiving chamber with a wall moved by fluid pressure therein, the movement of this wall being duplicated in the wall of a fluid transmitting chamber which is connected to the brake cylinder, and a device for controlling admission of fluid tothe rst chamber, this valve being so constructed and associated with other parts of the device that a close control of the movement of the movable wall and the discharge of uid from the fluid pressure transmitting chamber is attained.

Fig. 1 is asectional viewofa'preferred'form of my invention. Fig'. 2 is a fragmentary sectional view showing the valve member in another of its cooperating positions. v

3 is afrasmentary the'valve .parta in now restricting position.

The embodiment of my invention in the drawing has a fluid chamber l having a movable wall l, which, movement :from the ia shown, wm piace the liquid content et 'the cilamber l under pressure and foxce the lime through a serviceportimdinteroonnscungoondmtam an emansiblev unit such as the cylinder of a hydraulic brake, for example. The movable wall l is connected to a movable wall 9 forming one of the bounds of afluid receiving chamber lll. Valve means V are provided which may be controlled by an actuator ll, shown simply as a lever, for admitting fluid under pressure into the chamber Il, or releasing fluid therefrom, in order tomove the wall I and produce a proportionate movement of the wall 6.

In the -simple Aconstruction shown, the walls 6 and 9 comprise yopposite extremities of a piston member l2 axially movable in a shell I3 which provides a cylinder i4 in which the wall 9 is movable and a cylinder I5 in which the wall 9 is movable, these cylinders I4 and l5 comprising outer walls of the chambers 5 and I0. The piston member I2 comprises a tubular wall I6 having a diametrally reduced rightward end portion I1 on which the wall 9 is secured by means of a transverse cotter pin I8, there being a sealing member I9 for preventing leakage of uid through the joint formed between the wall 6 and the diametrally reduced portion I1 of the tubular wall I6. The service port 'l is formed in a closure plate 20 which forms an end wall for the chamber 5 and is provided with a sealing ring 2l. A chamber 22 for reserve fluid may be formed on the cylinder Il, this chamber 22 communicating with the chamber 5 through an opening 23. The movable wall 6, wh'ich forms a piston slidable in the cylinder Il, has a peripheral seal 24 shown as a ring of synthetic rubber resting in a peripheral channel in 'the mov-` able wall 6.

urges the piston member l2 leftward into the position in which it is shown in Fig. 1.

The intermediate portion 28 of the shell I3 cooperates with the piston member l2 so as to provide therebetween a fluid inlet chamber 21 and a fluid outlet chamber 28. These chambers 2l and 28 are'annular and are preferably formed Further objects and advantages of the invenby channels 29 and 30 in the circumference of the piston member l2. -The inlet and outlet UNITED STATES- PATENTHL'QFFIQE A compression spring 25, placedbetween the end cap 20 vand the movable wall 6,

is shown in Fig. l. Q therein a passage 41 which connects thel fluid of such axial dimension that they will be always` in communication with the ports 34 and. 85 dura,seo,svs l done, the shoulder 89 of the member 39 will close .the .-fluid.,. releasing ports`4 42 and the shoulder 48 will occupya posjitlongto thefrightfof the fluid ing all of the operative positions of the piston" member I2. i,

T'he valve means V comprises a part 38 having movement corresponding tothe movement of the movable walls 8 and 9, and a part 39 having movement in accordance with the movement o l' .the actuator II.v .The part 38 comprises a cylindrlc sleeve set into the leftward end of an opening ,or bore 49 which extends from end to end of the" piston member I2.V The sleeve or cylinder 38 has fluid admission valve ports' 4I which communicate with the fluid inlet chamber 21 and fluid release valve ports 42 which connect theinner face `of, thesleeve 38 with the Y .fluid outletchamber 28.1

y, The part 39 of the valve V, which is connected't the actuator II, comprises ai plunger 43,

equippedwitna. sealing ring 44, which is Vslidablepin the'b'ore or opening of the piston member I2.' A compression spring 45 is disposed between the leftward end of the plunger 43 and a yperforated plug 48 which is held in theprightward end o f the bore 49 by the cotter pin I8, this springyieldably urging the valve part 39 leftward toward the retracted position in which it 'I'he valve member 39-has pressure receiving chamber I9 'at all times with a zone inside the valve sleeve 38. The leftward end of the passage is at all times connected to the chamber IIl through .a groove 41 in the surface of the fpart 39 and the rightward end of the passage 41 comprises an annular channel 48 of axial length slightly less than the axial distance between the ports 4I and 42, so that when the valve part 39 is in the flow restricting position thereof, shown in Fig. 3, the shoulders 49 and 59 at the ends of the channel 48 will close the ports'4l and 42. The actuated valve part 39 has a cylindric portion 5I which projects through an opening 52 in the end wall 53 o1' the shell I3 and has thereon a snap ring 54 within the chamber I Il, which passes over.` the groove 41 and is positioned so as to engage the end wall 53 so as to limit the leftward or outward movement of the valve part 39. When the parts of the device are in the retracted or inactive position shown in Fig. .1, the ring 54 is spaced from the leftward end of the piston member I2 a distance whch will permit valve actuating movement of the part 39 before engaging the leftward end of the piston member I2.

When the device is in inactive condition as I shown in Fig. 1, the passage 41 communicates through the port 42 with the outlet chamber 28 which is connected through the conduit 31 withsuch as areservoir, so

a zone ofv low pressure, that low pressure exists in the chamber I0. At this time the shoulder 49 closes the fluid admission port 4I. At this time therefore the spring 25 holds the piston member I2 in its leftward o1 retracted position shown in Fig. 1.

When it is desired to operate the brake or other expansible unit to which the device is connected through the conduit 8, the actuator II vinto the fluid pressure receiving chamber I0, and `rightward movement of the piston member I2 will beacomplished. The rightward end of the piston member I2, formed by the movable wall 8, will, place the fluid in the chamber 5 under pressure and will force some of this fluid out through'the service port 1 andthe conduit 8 leading to the device which is to be operated. Thel force required to initially move the member 39 inprightward direction `is not large, owing to the low pressure in the chamber 5, and as pressure is built up in the chamber 5, a'proportionate pressure will be transmitted through the plug 46 to the rightward end of the plunger 43. Ordinarily this build-up in pressure against the rightward endl of the plunger 43 will tend to shift the valve part 39 a short distance leftward or outward against the rightward force applied to the actuator II by the operator. This slight leftwardpmovement of the valve part 39 will be felt by the operator who will then initiate an addi- Y tional muscular effort against the actuator Il is moved in rightward direction so as to shift the valve part 39 rightward into a position wherev in the ring or shoulder 54 engages the leftward end of the cylinder membery I2. When this is to resist leftward movement of the valve part :I9 and to urge the valve part 39 rightward in accordance with the braking effect desired, which the operator will determine not only from the change in movement of the vehicle or aircraft, but also from the reacting force or feelback felt through the actuator II.

As long as the operator holds the valve part 39 in the relative position in which it is shown in Fig. 2, which will require a gradual increase in the pressure applied to the actuator I I to move the valve part 39 rightward at the same rate as the rightward movement of the piston member I2, theadmission valve port 4I will be main- `tained opened and in communication with the chamber I0. But, should the valve part 39 be held substantially sationary, or should there be' a leftward movement thereof either due to a build-up in pressure against the rightward end thereof or a release in the force applied thereto through the actuator II, the relative movement of the valve part 39 and of the sleeve 38, movement of which is controlled by the movement of the piston member I2, will bring the shoulders or closures49 and 50 into the flow restricting position thereof shown in Fig. 3, wherein both ports 4I and 42 will be closed so that there will be no further feeding of fluid under ipressure into the chamber I0 and release of fluid from the chamber III cannot occur. At this time a volume of uid in the fluid pressure receiving chamber III will be held constant and 'of the area presented rightward by the plunger 43 forming the rightward end of the valve part 39. Should there be a build-up in pressure in the chamber 5, the same will be immediately felt by the operator, and should the operator desire to release the braking eilect, he need only slightly diminish the'force applied rightward through aseo-,srs

the actuator il so as'to permit a small leftward movement oi' the valve part 3| from the position in which it is shown in Fig. 3,- thereby opening the fluid releasing ports so as to permit an amount of fluid to escape from vthe chamber Il into the fluid outlet chamber 2l which communicates through the conduit 31 with a zone of low fluid pressure. When the piston member il is in an intermediate position and the valve parts l! and 3l are in the relative positions thereof shown in Fig. 3, a movement of the valve part Il either rightward or lcftward from the position in'which it is shown willresult in a like movement oi' the pistonmember I2 to bring the valve parts Il and l, back to the flow restricting position thereof. i

A feature of the invention is that the movable walls t and 9 may be of diil'erent diameters or areas, and when in use on aircraft. the movable wall'i may have an area which is a multiple of the area of the leftward end of the piston mem# ber I2, so that the quantity ofiiuid transmitted from .the vchamber 'l through the service port 1 will be large in 4volume as compared to the fluid fed into the chamber III at highpressureto oprate the device. 'Ihe feed conduit It may be Y connected to the hydraulic supply system of the aircraft carrying therein hydraulic uid at a pressure often in excess of one thousand pounds. The opposite ends of the piston member I2 may be designed so that under these conditions the fluid discharged from the chamber may have a maximum pressure of around three hundred and fifty pounds with the valve ports ll fully opened. Not only does the cooperative arrangement of the parts shown give rapid operation of the brakes and sensitivity of control, but it also provides quick release of pressure from the valve cylinders, owing to the large volume of fluid drawn into the chamber I when the piston member I2 moves leftward, as compared to the volume of uid which must be discharged from the chamber l0.

I claim as my invention:

1. In a fluid operated device of the character described, for applying uid under pressure to an expansible unit, and adapted to be controlled by an actuator, the combination of: a double ended piston member having an opening lengthwise thereof, said piston member having axially -spaced inlet and outlet ports connecting said opening with axially spaced circumferential faces of said piston member; means forming a pressure receiving cylinder to receive the front end of said piston member; means forming a pressure transmitting cylinder to receive` the rear end of said piston member, said pressure transmitting cylinder having a service port for connection to a device which is to receive fluid under pressure; a cylindric wall cooperating withthe exterior of said piston member to form in axially spaced relation a fluid inlet chamber and a fiuid outlet. chamber continuously connected -respectively with said inlet and outlet ports;

valve means for controlling a flow of fiuid into and out of said pressure receiving cylinden comprising a valve plunger extending into said opening of said piston member and being axially movablel therein between fluid releasing, flow restricting, and fluid admitting positions, said plunger having a depression intermediate the ends of its external face, therel being passage means to connect this depression continuously to having shoulders at theends of said depression spaced Aaxially a distance less than the axial distance between said inlet and outlet ports of said piston member positioned so as to close both said inlet port and said outlet port when said plunger is in said flow-restricting position there. of'so as to open only said outlet port to communication with said depression whenv said plunger is in said iiuld releasing position and so as to open only said inletport to communication with said depression Awhen said plunger is in said fluid admitting position.

. 2. In a fluid operated device of the character described, for applying fluid under pressure to `an expansible unit, and adapted to be controlled by an actuator, the combination of: a double ended piston member having an opening from end to end thereof, said piston member having axially spaced inlet and outlet ports connecting said opening with axially spaced circumferential faces of said piston member; means forming a pressure receiving cylinder to receive the front end of said piston member; means forming a pressure transmitting cylinderto receive the'rear f end of said piston member, said pressure transmitting cylinder having a service port for connection to a device which is to receive fluid under pressure, and a cylindric wall cooperating `with the exterior of said piston member to form in axially spaced relation a fluid inlet chamber and a fluid outlet chamber continuously connected respectively with said inlet and outlet ports; valve means for controlling a flow of uid into and out of said pressure receiving cylinder comprising a valve plunger extending into said opening of said piston member and being axially movable therein between fluid releasing, flow restricting, and fluid admitting positions, said plunger having a depression intermediate the ends of its external vface, there being passage means to connect this depression continuously to said pressure receiving cylinder, said plunger having shoulders at the ends of said depression spaced axially a distance less than the axial distance between said inlet and outlet ports of said piston member positioned so as to close both said inlet port and said outlet port when said plunger is in said' flow-restricting position thereof, so as to open only said outlet port to communication with 'said depression when said plunger is in said fluid releasing position and so as to open said pressure vreceiving cylinder, said plunger 15 only said inlet port to communication with said depressionwhen said plunger is in said vflluid admitting position; means connecting said plunger to said actuator; spring means operating between said plunger and said cylinder member to move said plunger toward said fluid releasing position thereof; and a shoulder on said plunger engageable with said piston member when said plunger is in said fluid admitting po- A sition, whereby movement of said plunger may be transmitted to said piston member.

3. In a fluid operated device of the character described, for applying fluid under pressure to Outer ends of said inlet and outlet ports; means forming a pressure receiving cylinder to receive -tively a fluid inlet chamber and a fluid loutlet chamber, and .iiuid inlet and outlet openings respectively continuously communicating through said cylindric wall with said inlet and outlet chambers; valve means torcontrolling a flow of iiuid into and out of said pressure receiving cylinder comprising a valve plunger extending into axially movable therein between fluidV releasing, ilow restricting, and fluid admitting position, said plunger havingfadepression intermediate the ends of its external face, there beingv passage means to connect this depression continuously to said pressure receiving cylinder, said plunger having shoulders at the ends otsaid depression spaced axially a distance less than the axial distance between said inlet and outlet ports of said piston member positioned so as to close bothsaid inlet port and said outlet port when said plunger is in said flow-restricting position thereof, so as open only said outlet port to communication with said depression when said plunger is in said fluid releasing position and so as to open only said inlet port to communication with said depression when said plunger is in said fluid admitting position.

f 4. In a fluid operated device of the, character described, for applying iiuid under pressure to an expansible unit, and adapted to be controlled by an actuator, the combination of: a double ended piston member having an opening from end to end thereof, said piston member having axially spaced inlet and outlet ports connect--v ing said opening with axially spaced circumferential faces of said piston member, and said piston member-having axially spaced external annular channels communicating respectively with the outer ends of said inlet and outlet ports; means forming a pressure receiving cylinder to receive the front end of said piston member; means forming a pressure transmitting cylinder to receive the rear end of said piston member, said pressure transmitting cylinder having a servfice port for connection to a device which is to receive fluid under pressure, and a cylindric wall cooperating with the exterior. of said piston member to form of said annular channels respectively a fluid inlet chamber and a uid out- 1 let chamber, and iiuid inlet and outlet openings respectively continuously communicating through said cylinder wall with said inlet and outlet' chambers; valve means for controlling a flowof fluid into and out of said pressure receiving. cylinder comprising a valve plunger extending into said opening of said piston member and bef ing axially movable therein between fluid releasing, flow restricting, and fluid admitting positions, said plunger having a depression intermediate the ends of its external face, there being passage means to connect this depression continuously to said pressure receiving cylinder, saidplunger having shoulders at the ends of said depression spaced axially a distance less than the axial distance between said inlet and outlet ports of said piston member positioned so as to close both said inlet port and said outlet port when l said plunger is in. said iiow-restricting-position said opening of said piston -member and being thereof, so as to open only said outlet port to communication with said depression when said plunger is-in said iiuid releasing position and so as to open only said inlet port to communication with said depression when said plunger is in said fluid admitting position; means connecting said plunger to'said actuator; spring means operating between said plunger and saidvcylinder member to move said plunger toward said fluid releasing 4position thereof; and a shoulder-A on said plunger engageable with said piston memberv when said plunger is in said uid admitting position, whereby movement of saidplunger maybe transmitted to said piston member.

i 5. In a fluid operated device of the character described, for applying fluid `under pressure to `ari expansible unit, and adapted to be controlled by an actuator, `the combination of: a double ended piston member having an opening from end to end thereof, said pistonrmember having axially spaced inlet and outlet ports y,connecting y said opening with axially spaced circumferential faces of said piston member, andsaid piston member'having axially spaced external annular channels communicating respectively with the outer ends of said inlet and outer ports; Ameans forming a pressure receiving cylinder to receive the front end of said piston member; means e forming a pressure transmitting cylinder to re- 4 ceive the rear end of said piston member, said pressure transmitting cylinder having a service port for connection to a device which is to receive fluid `under pressure, anda cylindric wall cooperating with the exterior of said, piston member to form of said annular channels respectively a iluid inlet chamber and a fluid outlet chamber. and fluid inlet and outlet openings respectively continuously communica-ting through said cylindric wall with said inlet and outlet chambers; valve means for controlling a flow of fluid into and out of said pressure receiving cylinder comprising a cylindric bar of constant diameter forming a valve plunger extending into said opening of said piston member and being axially movable therein between fluid releasing, flow-restricting, and fluid'admitting positions, said plunger having a depression intermediate the ends of its external face and a diagonal passage extending through said plungerso as to connect this depression 'continuously to said pressure receiving cylinder, said plunger having shoulders at the ends of said depression spaced axially a distance less than the axial distance between said inlet and outlet ports of said piston member positioned so as to close both said inlet port and said outlet port when said plunger is in said flow-restricting 4position thereof, so as tov open only said outlet port to communication with said depression when said plunger is in said fluid releasing position and so as to open only said inlet port to communication with said depression when said plunger is in said fluid admitting position; means con-- necting said plunger to said actuator; spring means operating between said plunger and said cylinder member to move said plunger toward. sa'id fluid releasing position thereof :and a ring. detachably secured on said bar adjacent the front end of said piston member to form a shoulder on said plunger engageable with said piston member when said plunger is in said fluid admitting position, whereby movement of said plunger may be transmitted to said piston member.

GILBERT E. PORTER. 

